Teflon Tape / Rector Seal?

I let me pump run mostly dry because I forgot to switch the jandy valve back from using the spa last night so it ran all day after is bascially drained the spa into the pool. Now I have a leak at the pump discharge going into the multi port valve. My question is what is recommended as a thread sealant on the pump discharge fitting. When my pool was originally built, (15 years ago) a white liquid of some sort was used that hardened / dried but could still be broken for replacment, unlike any PVC glues etc. When I have encountered this before (stupid me letting the pump run dry) it seems that I always developed a leak at the discharge threads. What material is recommended for sealing those threads properly, long term? Obviously this is a high vibration area but Rector seal does not seem to really set up firm nor have other sealers I have used previously.